The GL3Web.c file replaces the GLESv2 library in the compile and link process. It intercepts the gl function calls and spits out gl. WebGL2 javascript. This is mostly a one to one subsitution, but additional code handles gl C pointer data conversion to javascript text arrays.
The Javascript Webgl output together with a HTML header and footer creates a HTML webpage copy of the OpenGLes3 screen draw. Have fun.
I have included one of my test page HTML output.
Chief Engineer